Chavín de Huántar Archaeological Acoustics Project

Chavín de Huántar is a monumental World Heritage archaeological site [1] in the Peruvian highlands predating Inca society by over 2000 years. Since 1995 Professor John Rick of Stanford University and teams have been excavating the site [2], revealing peculiar and unique architectural features in both surface and underground structures. It is the underground structures, a complex of labyrinthine galleries and corridors, that are of particular interest to this project, because explanations for their purpose and function have led to Rick’s hypothesis that they were constructed, at enormous cost in labor, to establish social hierarchy through sensory manipulation in the context of religious ritual: a priest-elite over the novitiates.

In 2001 Rick discovered in one of the galleries twenty engraved ceremonial Strombus (conch)
trumpets, some of which showed (through wear) use over several centuries. This important
discovery reinforced his hypothesis that the acoustic properties of the underground part of the site
were fundamental to the ancient ritual and perhaps even a determinant in architectural layout and
design. One of the important (and enticing) questions is whether there is an acoustical
relationship between the Strombus trumpets and the dimensions and layout of the underground
galleries. That is, are the acoustic properties of the Strombus trumpets in any way coupled to the
resonant frequencies and temporal features of the galleries and corridors? Finding an answer to
this question will provide Rick with data to further elaborate and refine his hypothesis regarding
the importance of sensory manipulation in Chavín ritual.

Since an important area of research at CCRMA is physical modeling of acoustic sources and
reverberant spaces, we saw the opportunity to join two disciplines with the purpose of extending
Rick’s three-dimensional measurements and CAD renderings of the site to include physical
models of the site’s acoustics, with excitation sources such as Strombus trumpets, rushing water
through canals both above and beneath galleries, and the human voice. Acoustic measurements
and models of a site can be used to archive site acoustics, estimate the acoustics of inaccessible or
alternative site architectures, and reconstruct original site acoustics; they may also be used to
corroborate aspects of rituals suggested by other archaeological data. Measurement and modeling
may be used to understand the implications of auditory experiences within these galleries as
related to the role of the site in developing religious authority.

It is notable that because Chavín de Huántar presents intact enclosures primarily without post-
period modification, acoustic measurements can be made throughout much of the site that closely
reflect period conditions. Such an opportunity to archive relatively unmodified ancient
architectural structures is rare. However, this opportunity may soon be altered: Chavín de Huántar
is an important touristic attraction; thus the Peruvian government must make the underground
galleries safe for visitors, adding reinforcing structures that will irreversibly alter the acoustics. It
is therefore imperative that onsite measurements be made soon, precisely, and thoroughly.

The project is divided into three phases as shown below. Phase 3 represents the ultimate goal: a complete and
site-independent virtual simulation over multiple loudspeakers, produced using a computer-based
model of the acoustics of the underground galleries and above-ground plazas. These acoustic
models will provide a rich research base with which to evaluate a variety of acoustic conditions,
architectural geometries, source placements and listening positions within the galleries. Such a
simulation can also be exhibited as an installation/virtual walkthrough, at both the Chavín
museum in Peru, and at Stanford, reconstructing an auditory-visual experience of the original
galleries.